167
EDITORIAL
The role of magnetic resonance imaging
in the management of schistosomal
myeloradiculopathy
O papel da ressonância magnética no manejo da mielorradiculopatia esquistossomótica
Leandro Tavares Lucato
Schistosomiasis is a chronic, parasitic disease caused by blood lukes (trematode worms) of the genus Schistosoma1. First reports of what most likely correspond to the disease were found in Egyptian medical papyri, and eggs of the worms were found in mummies2,3. In spite of being recognized more than 30 centuries ago, recent data indicate that more than 207 million people are infected worldwide, with an estimate of 700 million people at risk in endemic countries1. However, even outside endemic areas, its importance has been rising in recent years, since to-day’s highly mobile, interdependent, and interconnected world provides myriad opportunities for its spread.
Involvement of the central nervous system (neuroschistosomiasis) is caused by infection with S. mansoni, S. haematobium, or S. japonicum. Schistosomal myeloradiculopathy (SMR), usually related to S. mansoni infection, is the most frequently recognized presentation of neu-roschistosomiasis, although it is still considered underdiagnosed in endemic areas4.
Diagnosis of SMR is usually presumptive, relying on a positive epidemiology and pertinent neurological picture (spinal cord and/or nerve root involvement, most often the lower por-tions of the cord and cauda equina). It is also necessary to demonstrate the schistosomal in-fection and to exclude other causes of myelopathy.
here are undoubtedly a couple of issues related to demonstration of the infection: para-site load is small in SMR compared to other forms of the disease, causing diiculties in ob-taining positive stool samples (rectal biopsies present higher sensitivity, however); serological tests lack speciicity especially in endemic areas; and immunodiagnostic tests in the cerebro-spinal luid (CSF), although promising, need validation before their widespread use4.
In this scenario, magnetic resonance imaging (MRI) demonstrates high sensitivity but un-fortunately not high speciicity. However, MRI is a relevant tool, not only helping to increase the likelihood of SMR in a given patient but also in the potential recognition of other diseases mimicking it. Most commonly, one can ind enlargement of the lower spinal cord and/or cau-da equina roots, presenting hyperintensity in T2-weighted images and variable post-contrast enhancement5,6. his constellation of indings supports the diagnosis when associated with pertinent clinical and epidemiological data, especially when an elevated eosinophil count is present in the CSF analysis.
Patterns of gadolinium enhancement related to SMR, which can coexist in a single patient and even change during the course of the disease, include intramedullary nodules, lesions in the cord surface and enhancing thickened nerve roots5. In a small sample (three patients), a more speciic pattern was described, characterized by an ‘arborized’ appearance derived from central linear enhancement surrounded by multiple enhancing punctate nodules7. Taken together, these studies can advocate for the diagnosis of SMR when multiple enhancing in-tramedullary nodules are seen in the lower cord.
Vidal et al.8, in the present issue of Arquivos de Neuro-Psiquiatria, draw attention to a less common MRI picture in SMR. he presence of extensive cord compromise, manifested by T2-hyperintensity involving the whole spinal cord or its thoracic and lumbar regions, was ap-preciated in 10 out of 12 patients with MRI abnormalities; difuse enhancement was found in
Neuroradiologist, Instituto de Radiologia do Hospital das Clínicas da Faculdade de Medicina da USP, Fleury Medicina Diagnóstica, São Paulo SP, Brazil.
Correspondence Leandro Tavares Lucato
Avenida Doutor Enéas de Carvalho Aguiar 255 / 3° andar
05403-001 São Paulo SP - Brasil E-mail: ltlucato@uol.com.br
Conflict of interest
There is no conflict of interest to declare.
168 Arq Neuropsiquiatr 2012;70(3):167-168
eight of them, somewhat heterogeneous but distinct to the above described patterns.
Their findings certainly deserve some reflection on possible factors influencing the involvement of high spi-nal cord segments and the development of diffuse en-hancement. The most important mechanism to under-score is undoubtedly the immune response of the host to the presence of parasite eggs, probably directed towards a vasculitis mediated by eosinophils, immune complexes, or both; instead of the most frequently observed granu-lomatous reaction. The authors speculate that this is at
1. Schistosomiasis. Fact sheet N° 115. [Internet] [acessed 2011 Nov 20]. Available from: http://www.who.int/mediacentre/factsheets/fs115/ en/index.html#.
2. Ruffer MA. Note on the presence of “Bilharzia haematobia” in Egyptian mummies of the twentieth dynasty. Br Med J 1910;1:16.2.
3. Brier B. Infectious diseases in ancient Egypt. Infect Dis Clin North Am 2004;18:17-27.
4. Ferrari TC, Moreira PR. Neuroschistosomiasis: clinical symptoms and pathogenesis. Lancet Neurol 2011;10:853-864.
5. Saleem S, Belal AI, el-Ghandour NM. Spinal cord schistosomiasis: MR imaging appearance with surgical and pathologic correlation. AJNR Am J Neuroradiol 2005;26:1646-1654.
6. Peregrino AJ, Puglia PM, Bacheschi LA, et al. Diagnosis of schistosomiasis of the spinal cord: contribution of magnetic resonance imaging and electroneuromyography. Arq Neuropsiquiatr 2002;60:597-602.
7. Sanelli PC, Lev MH, Gonzalez RG, Schaefer PW. Unique linear and nodular MR enhancement pattern in schistosomiasis of the central nervous system: report of three patients. AJR Am J Roentgenol 2001;177:1471-1474.
8. Vidal CHF, Ferreira MLB, Azevedo-Filho HRC, Gurgel FV, Brainer-Lima AM. Extensive spinal cord involvement in magnetic resonance imaging evaluation on schistosomal myelitis. Arq Neuropsiquiatr 2012;70:210-213.
References
least in part related to the fact that patients come from a recent endemic area. Therefore, their exposition to the parasite is also recent, leading to a more exuberant im-mune response.
